浅谈航空航天用电线耐电弧试验方法

电线绝缘在干燥及潮湿环境下耐电弧传播试验可以评估电线绝缘在电环境下防止破坏的能力,因此,耐电弧试验成为航空航天用电线检测中非常重要的一项性能。介绍了航空航天用电线的耐干电弧、耐湿电弧试验,并对两种试验的方法及技术要求进行了描述。     

基于Verhulst模型的疲劳裂纹扩展公式

根据 dadn-ΔK 的关系曲线与Verhulst模型曲线的对应关系 ,导出了基于Verhulst模型的两个疲劳裂纹扩展公式 ,对工程实例的计算表明 ,导出的公式适合 dadn-ΔK 的关系曲线的整个区域 ,精度较高。     

蜂窝移动定位系统定位精度提高算法的研究进展

提高蜂窝移动定位系统的定位精度是定位技术在CDMA系统中广泛应用的关键。针对提高移动定位精度算法的研究,分别从基本定位算法、非视距传播误差消除算法、抗多径干扰时延估计和抗多址干扰算法、数据融合定位方法等几个方面进行了详细的分析和讨论,综述了该领域的最新研究进展,提出了自己的观点。最后对移动定位精度提高算法研究的未来进行了展望。     

双芯光子晶体光纤耦合长度研究

利用光束传播法模拟了光波在不同结构的双芯光子晶体光纤内的传输状况,并计算了其耦合长度。分析了耦合长度随光波长、孔半径变化的一般规律;当双芯光子晶体光纤的结构一定时,耦合长度随波长增大而减小;孔间距和波长不变时,耦合长度随空气孔半径增大而增大。     

传播模型优化的研究

本文针对现有条件下无线网络规划的问题提出了传播模型优化的重要性,并通过深入分析传播模型优化的概念、方法和特点提出了其对移动通信设计的作用,同时给出了对我国进行传播模型优化的策略。     

扇形中深孔爆破块度预测的神经网络法

针对现有爆破块度预测模型存在的不足,应用神经网络理论,研究了具体矿岩条件下的扇形中深孔爆破块度预测的神经网络方法.构建了三层前馈型神经网络结构,并根据扇形中深孔爆破实例,采用BP 算法对网络进行了训练,建立了具体矿岩条件下的扇形中深孔爆破块度分布与其影响因素间的非线性映射关系.采用测试样本对模型进行了测试,结果表明,所建立的模型用于扇形中深孔爆破块度的预测是可行的,模型精度是可靠的.     

On the impact of a more realistic physical layer on MANET simulations results

Network simulation tools are frequently used to analyze the performance of MANET protocols and applications. Currently they offer only simple wireless communication models that neglect many radio propagation effects. In this paper, we integrate a more realistic physical layer model into a simulation tool. It consists of a radio propagation model and a model of wireless transmission errors. They have been evaluated against real-world measurements. We prove that such more realistic models change simulation results considerably. To the best of our knowledge, no other study of MANETs has been performed so far with such a detailed physical layer model. Hence, this paper also gives new insights on the performance of MANETs in real outdoor environments.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Influence of Temperature on Shockley Stacking Fault Expansion and Contraction in SiC PiN Diodes

While Shockley stacking fault (SSF) creation and expansion within 4H-SiC bipolar devices is well known, only recently was it observed that this expansion and the associated increase in the forward voltage drop (V _f) could be completely reversed via low-temperature annealing. Here we report the temperature dependence of the recovery rate of the V _f drift via annealing, reporting an activation energy of 1.3 ± 0.3 eV. The V _f drift was observed to saturate following extended electrical stressing, and it was observed that the value of V _f at this saturation was inversely proportional to the stressing temperature. We also observed that SSF and V _f drift recovery could occur in highly stressed diodes at elevated temperatures even under high current injection conditions (14 A/cm²).     

用薄膜光学理论研究布拉格光纤的传输特性

用薄膜光学的等效导纳方法和阶跃光纤的几何光学理论研究布拉格光纤的传输特性.①设计出了反射率达99.99%包层的厚度、层数;②分析了传输效果随波长、层数、入射角的变化;③得出光束的数值孔径小于0.15时,反射率大干99.99%.这一研究对布拉格光子晶体光纤的实际加工及与阶跃光纤耦合具有重要理论意义.